[sdiy] ammonium persulfate safety

[Paul Higgins]

Hi all,

All this talk about melting down your lab bench/microwave/etc. in the 
name of PCB construction got me to thinking about something someone 
once told me.  That is, ammonium persulfate is not stuff you want to 
keep bottled up in storage--it releases lots of O2 or something.  Does 
this sound plausible?  Has anyone had any leaking/bursting bottles?

Most of my schooling was in biology, not electronics, and my main 
experience with APS (as it is known in biochem labs) was its use as a 
free-radical generator for various reactions (setting certain resins 
for gel electrophoresis, etc.).  Of course, I know that it is used for 
PCB etching as well; people seem to like it due to it being a clear 
liquid so that you can see the progress of etching.  But the stories I 
used to hear about its instability and out-gassing of O2 have kept me 
from using it.  In the biochem lab, we always used up most of the APS 
we mixed, and usually decomposed the rest (or put it in an open hazmat 
bottle in the fume hood), so I never had the opportunity to see if the 
stories about exploding bottles were true.

So, my question is, is this stuff shelf stable?  Like FeCl3, for weeks 
or months at a time?

TIA,

-PRH

Paul R. Higgins
email: higg0008 at tc.umn.edu